As head of the investment banking division, Carsten Kengeter is responsible for risk control. He has also been viewed as one of the top candidates to take the helm after chief executive Oswald Gruebel steps down.

The Swiss bank's chief executive Gruebel is expected to host an investor day on November 17 to discuss a "major restructuring of UBS's investment bank."

It's unclear at this time what that restructuring will be exactly, but some think the investment bank business will be pared back.

The trading loss may also renew calls in Switzerland for UBS to drastically scale down its investment bank or even spin it off entirely. Since UBS's near-collapse three years ago, Swiss regulators have fretted about UBS's ambitions to rebuild the investment bank.